In its bid to further challenge Google on the online advertising front, Microsoft Nov. 2 announced a deal with OpenX Technologies (an "independent ad server for Web publishers," according to Microsoft's news release) that will have the two companies referring publishers to one another, as well as cross-marketing.

The companies claim that OpenX's base of 150,000 Websites delivers 300 billion ads per month. As part of the partnership, OpenX will use that channel to promote Microsoft's Content Ads, which Redmond no doubt hopes will be a Google AdSense killer.

The agreement reveals more fully Microsoft's plans to take on Google, the dominant player in online search and advertising. Instead of going it alone, Redmond is partnering with companies that have already established themselves in the space. Look at the Yahoo agreement of July: Yahoo takes over worldwide online sales duties for both companies, while Microsoft's Bing search engine powers Yahoo's search. Bing's market share will likely more than double once the deal's completed, giving Microsoft a far more rapid boost than if it had tried to increase its share a hard-fought point at a time.

Given that AdSense remains integral to Google's overall revenue model, however, you can expect a tooth-and-nail fight between the search engine giant and Microsoft for online ad dollars. And, as evidenced by everything from this summer's marketing campaign for Bing to Microsoft's increased focus on porting traditionally desktop-bound programs like Office into the cloud, Microsoft is more and more aware that it absolutely must win the online battle.

I'm betting that Microsoft's OpenX deal will not be the end of its online partnerships. What better way, really, for Microsoft to rapidly gain the market share it needs?